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(No Model.) 2 sheefs-sheet 1. M. G. FARMER.

TELEPHONE TRANSMITTER. No. 316,133. Patented Ap1.21, 1885.

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M. G. FARMER.

TELEPHONE TRANSMITTER.

No. 316,133. Patented Apr. 21, 1835.

Miren Salaires PATENT Orme-n;

MOSES G. FARMER, OF NEVPORT, RHODE ISLAND.

TLEPHoNE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 316,133, dated April 21, 1885..

Application filed October 29, 1884. (No model.)

My invention relates to telephone-transmitters in which a series of freely and independently pivoted contacts 'constituting one of the electrodes rest upon the contact or electrode carried by'or connected with the diaphragm, and kno-wn as multiple-contact telephones.

l The chief object of my invention is to improve the construction of apparatus of this kind, whereby the impulses or u'ndulations of current will be amplilied, and this I do by using a pivoted lever connected with vthe diaphragm so as to be moved or oscillated by the vibrations of the same, and carrying a contact bar or electrode at each end upon which pivoted contacts rest. From this construction it follows that by the oscillation of the lever the contact-pressure between one bar or electrode and the pivoted contacts resting thereon will be diminished at the same time that the con tact-pressure between the other electrodes is increased, and conversely. By taking advantage of this action I obtain in two circuits, or two branches of the same circuit, simultaneous undulations or impulses of opposite character that may be applied to produce, by their conjoint effect, more positive and marked results than can be practicably obtained by the ordinary forms of instrument.

In order that I may avoid using any portion of the lever or its bearings as part of the circuit, I arrange each series of pivoted contacts in two independent groups, and make the circuit from one group to the other through the bar or electrode upon which they rest. An instrument thus constructed requires little or no change of adjustment and is capable of long-continued use. rlhe details of the construction of this device I will now describe by reference to the accompanying drawings, in which- Figure 1 is aplan view of the instrument with a portion of the inclosing-case removed.

Fig. 2 is a side elevation ofthe same with the case in section. Fig. 3 is adiagram of the instrument and circuit-connections.

On the base A of the instrument are set two uprights, aa, and in these is mounted a rockshaft, B.

O is a circular disk of ebonite, hard rubber, or the like, fixed to the middle of the shaft B.

D E are vertical arms secured to the faceof the disk O.

To the arm D are connected spiral springs S S, of equal tension, and adjustahle,if necessary, which serve to maintain arm D in a vertical position. A'rm E is connected by the link F to the diaphragm G, properly supported over the orifice or mouth-piece H in the end of the case B. These several connections are made in such manner that the vibratory movements of the diaphragm will impart to the `rock-shaft a corresponding oscillatory movement, and well understood mechanical means are employed which will reduce to a minimum the amount of lost motion.

K L are horizontal arms attached to the face of the disk O. rlhey are preferably composed each of two strips of light metal bent at right angles in opposite directions to form the supports M N. The right-angled supports M N may obviously be independent pieces of metal secured to the arms K L.

On opposite sides of the rock-shaft, and preferably at a short distance beyond the sup.- ports or bars M N, are the standards c d e f. Each carries a short metal bar, r/,to which are pivoted loosely a series of conducting-plates l or strips, O Ol P P, which rest upon the supports M N.

The instrument is provided with four binding-posts, m m n u', connected in the following manner: post m with standard c, post m with standard d, n with e, and n with f.

XVhen the diaphragm is Vibrated by a person speaking against the same, the shaft B is oscillated. This movement being considera bly amplied at the ends of the bars K L, the conditions of contact between the supports M N, which form one set of electrodes, and the pivoted plates or strips forming the others are varied. In other words, the depression of loo time the elevation of N improves the contact between itself and the pivoted plates bearing on it, so that while the resistance of the circuit through one set of electrodes is increased, through the other it is lowered, and the impulses of current thus produced may be applied to the reproduction, in a telephone-line, of impulses ofgreater power than are obtained under ordinary conditions. One way of utilizing these impulses is shown in Fig. 3, in which the electrodes of the instrument are shown. One of the wires from a local battery, T, is branched-to the posts m n. The other is connected to the center of the primary wire of an induction-coil, I, and through it to the posts m a. The secondary wire is grounded and includes the receiving-instrument R. Normally,the current divides equally through the two branches of the local circuit, the resistances being balanced. By the oscillation of the shaft B the resistances are varied, and an unequal distribution of current being in this way effected the magnetic conditions ofthe core of the induction-coil are disturbed and current induced in the secondary or line wire.

I In constructing this apparatus any of the usual forms of diaphragm may be used. The other moving parts, including the arms attached'to the disk C and the pivoted plates or electrodes, should be as light as is consisteut with strength and good conductivity. I prefer to make these parts of aluminium, but other materials may be used. The pivoted electrodes, for example, are advantageously made of carbon.

I am aware that an electrode composed ofa multiplicity of plates resting on another electrode is not new. The apparatus which I have invented involves, however, certain important features of novelty not heretofore embodiedin any instrument of this kind. Among these, as I have above pointed out, is the use of two sets of contacts or electrodes bearing on the same vibratory electrode-support. This arrangement I have foundto give greatly improved results; also the combination, with the diaphragm, of the rock-shaft, the arms extending therefrom, and the two sets of electrodes operated by them. It is of course obvious that the number of arms and electrodes may be increased, but two will, under ordinary circumstances, prove sufficient.

l. In a transmitting-telephone, the combination, with an oscillating lever connected with the diaphragm, of pivoted electrodes resting upon said lever on opposite sides of the fulcrum, as and for the purpose specified.

2. In a transmitting telephone, the combination, with an oscillating lever carrying metallic bars and connected with the diaphragm, of loosely-pivoted contact-strips constituting electrodes and resting upon the metallic bars, as set forth.

tion, with two independent electrodes or sets of contacts, of a metallic bar or support connected with the diaphragni,and circuit-connections by which the current is passed from one electrode or set ofcontacts to the other th rough the bar upon which they rest, as set forth.

4. In a transmitting-telephone,the combination, with an oscillating lever carrying metallic bars and connected with the diaphragm, of two electrodes or sets of contacts resting upon each bar, and circuit-connections by which the currents are passed from one electrode or set of contacts to the other through the bars upon which they rest, as and for the purpose set forth.

5. In a transmitting-telephone,the combination, with a rock-shaft, an insulating-disk carrying vertical arms,one connected with the diaphragm, the other with adj Listing-springs, and horizontal arms with metallic bars at right angles thereto, of pivoted conducting strips or plates constituting electrodes and resting on the metallic bars, as set forth.

6.' The combination,with the rock-shaft and insulating-disk,ofthe vertical arm E,and linkconnection with the diaphragm, the arm D, and opposing springs connected therewith, the horizontal arms with ends bent at right angles, and the pivoted electrodes resting upon the ends, as herein set forth.

In testimony whereofI have hereunto set my hand this'lth day of October, 1884.

MOSES G. FARMER.

Witnesses: l

W. FRIsBY, RAYMOND F. BARNES.

3. In atransmitting-telephone,the combina-f6 

